An Integrated Load Balancing Scheme for Future Wireless Networks

With the emerging IEEE 802.11n standard, the WLAN is poised as a promising ubiquitous networking technology to support multimedia applications where providing QoS becomes imperative. However, the 802.11 WLAN is not designed to support delay sensitive traffic. This problem is magnified during a handover and typically results in excessive handover latency and packet loss. In addition, a 802.11 WLAN handover process is predominantly based on the physical layer detection without QoS considerations. This often causes overloading of access points and consequently all its associated connections would suffer from high delay. The former can be resolved by reducing handover latency to achieve seamless handover and the latter can be mitigated by employing link layer detection in the 802.11 WLAN handover process and having an appropriate admission control scheme. Although the IEEE 802.11e standard supports prioritized QoS, it cannot guarantee strict QoS required by real-time services under heavy load. In this paper, we proposed an integrated load balancing scheme incorporating (i) QoS-based fast handover to support seamless handover by eliminating both detection and scanning phases from the 802.11 WLAN handover process; and (ii) soft admission control to protect QoS of existing connections when resources are low. This synergy allows us to perform QoS-related handover opportunistically and guarantees service QoS during and after handover respectively. Simulations showed that our proposed integrated load balancing scheme is capable of providing seamless handover and QoS provisioning for real-time VoIP services in terms of bounded delay and packet loss when considering multimedia traffic. Particularly, our proposed scheme exhibits both throughput and QoS fairness which jointly optimize overall system utilization.